1. Field of the Invention
This invention relates to a substrate for an ink jet recording head, an ink jet recording head and an ink jet recording apparatus provided with the recording head.
2. Related Background Art
As the support member of an ink jet recording head, use has heretofore been made of an Si support member, a glass support member or a support member of ceramics such as alumina.
An Si support member poses no problem in terms of its performance, but it is difficult using present-day techniques to manufacture, for example, an Si wafer which copes with the elongation or bulkiness of a recording head corresponding to the length of a side of recording paper of size A3 or A4 (Japanese standard), and it has also suffered from the problem of high cost. A glass support member has bad heat conductivity and therefore accumulates heat therein if the head drive frequency is increased, and insoluble matter can precipitate from recording liquid, and sometimes it becomes impossible to discharge the recording liquid. A ceramics support member, in the manufacturing process thereof, is liable to cause surface defects (i.e., surface defects such as pin-holes or projections of several .mu.m to several tens of .mu.m) which are very difficult to find by visual inspection or microscopic inspection and cannot be detected until films on the defects come off after film formation, and thus many defects occur during the film formation.
Also, with the ceramic support member, it is difficult to obtain a mirror surface having surface roughness of several tens of .ANG. or less, and usually they are used with a glaze layer provided on the whole of one surface thereof. This has sometimes led to the problem that the glaze layer cannot be made thinner than in the manufacture 40-50 .mu.m in the manufacture and therefore, as in the glass support member, it has sometimes led to the problem of heat accumulation.